I frequently hear nervous flyers say that they hear unfamiliar noises on the aircraft, well let me explain some of the common ones. That sound that you'll hear almost immediatley after takeoff is the sound of the landing gear being retracted. Later on in the climb the pilots will also retract the flaps with a similar kind of mechanical noise. Pilots use flaps on takeoff because they help the aircraft gain better lift at slow speeds. You will also hear the same sounds on landing. During the cruise portion of the flight you will sometimes hear chimes go throughout the cabin These are either used to get the attention of the passengers before and after takeoff and other times there will be a different chime for a crew to crew message. One thing that the chimes do not signal is that there is an emergency so there's not much to be worried about. Turbulence is probably one of the most common (yet harmless) things that scare many passengers. if you're sitting by the wing and you encounter turbulence you can see the wing moving. Don't worry it's not going to snap off. The wings are designed to move up and down like that to prevent stress to the wing struture so the bending is actually a good thing.